Sorry but you're very wrong here! Punching somebody is NEVER acceptable outside of defending yourself from bodily harm.
Don't say you're sorry when you're not.
Absolutes like that don't really exist. There are times where physical intervention can prevent worse outcomes, and in those cases the law and morality side with the person that hits first and neutralizes the situation.
If a robber breaks into my home, grabs my daughter as hostage, and tries to use her as a shield, are you saying that I should wait until he kills her before I kill him?
People who are harassed, as Buzz was by this person, feel the same threat I would feel in the above scenario after that much harassment. I feel it was well within Buzz's right to sock the dude.
Restraining orders are only valid in a single jurisdiction, because the courts that issue them have limited reach. This guy followed Buzz all over the Earth. And, usually, one must be the victim of a violent attack in order to attain a restraining order, anyway, so Buzz probably would never have been able to even get one. Buzz had used words, and asked nicely that the fella to go away many times. The guy wasn't hearing him, so Buzz used a language the guy COULD hear, which is the language of I'll Break Your Fuckin' Nose, Asshole, Now Leave Me Alone!
And hey, the guy leaves him alone, now.
Magic.